1. Field of the Invention
The present invention relates to a vibration damping device used as an automobile engine mount or the like, for example, and particularly relates to a fluid-filled vibration damping device having a fluid chamber in which non-compressible fluid is enclosed in the interior.
2. Description of the Related Art
Vibration damping devices have been known which are interposed between members constituting a vibration transmission system for connecting these members, or alternatively for supporting one member on the other, in a vibration damping fashion. This vibration damping device includes: a first mounting member attached to one member of the vibration transmission system; a second mounting member attached to the other member of the vibration transmission system; and a main rubber elastic body elastically connecting the first and second mounting members. Furthermore, as one type of vibration damping device, a fluid-filled vibration damping device having a plurality of fluid chambers which have non-compressible fluid enclosed in the interior is known. In the fluid-filled vibration damping device, a fluid chamber filled with a non-compressible fluid is divided by a partition member into a first fluid chamber and a second fluid chamber. Furthermore, the partition member is provided with a holding area in which a movable membrane is installed with an outer circumference part grasped by the partition member. On both surfaces of the movable membrane, pressures of the first fluid chamber and the second fluid chamber are applied through communication holes formed on the partition member. Thus, minute deformation or minute displacement of the movable membrane is caused based on the relative pressure difference between the first fluid chamber and the second fluid chamber, thereby exhibiting a target vibration damping effect. U.S. Pat. No. 7,188,830 discloses an example of active type of fluid-filled vibration damping device, wherein an excitation force of an actuator applied to an excitation fluid chamber is transmitted to the pressure receiving chamber by the minute displacement of the movable membrane, exhibiting an active vibration damping effect.
With the fluid-filled vibration damping device as disclosed in U.S. Pat. No. 7,188,830, the partition member is constituted by a plate form first partition plate and second partition plate overlapping in the thickness direction, so that the holding area is formed between that first partition plate and second partition plate, and the movable membrane is housed within the holding area.
Meanwhile, when the work of combining the first partition plate and the second partition plate (partition forming work) is performed in air, there is the risk that air will remain between the first partition plate and the second partition plate. Therefore, it is necessary to perform this work inside a water tank filled with the non-compressible fluid, making the partition member forming work difficult. In particular, when the movable membrane is grasped at its outer circumference part between the first partition plate and the second partition plate, it is easy for air to remain. This requires doing attachment work within a non-compressible fluid. Furthermore, once the partition member is taken from the water tank into air, air penetrates again. Thus, the work of attaching the partition member to an integrally vulcanized product of the main rubber elastic body must be performed simultaneously without taking the partition member out from the water tank. As a result, complex work is required within fluid.
Additionally, at the stage before the combining work within fluid, the partition member is divided into at least three parts of the first partition plate, the second partition plate, and the movable membrane. Therefore, there was the problem that parts management and transport were troublesome.